Complex Magnetic Ordering in the Oxide Selenide Sr2Fe3Se2O3.
Complex Magnetic Ordering in the Oxide Selenide Sr2Fe3Se2O3.
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DOI：
10.1021/acs.inorgchem.8b01542
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发表时间：
2018-07
影响因子：
4.6
通讯作者：
S. Cassidy;F. Orlandi;P. Manuel;J. Hadermann;A. Scrimshire;P. Bingham;S. Clarke
中科院分区：
文献类型：
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作者：
S. Cassidy;F. Orlandi;P. Manuel;J. Hadermann;A. Scrimshire;P. Bingham;S. Clarke
Sr_2Fe_3Se_2O_3是一种局域瞬间氧化铁硒化合物，其中Fe2+离子的两个不寻常的配位形成2：1的两个亚晶格。在室温顺磁区，该化合物采用首次报道的Sr_2Co_3S_2O_3的晶体结构，其空间群为PBAm，a=7.8121，b=10.2375，c=3.9939，Z=2。三分之二的铁离子占据的亚晶格(Fe_2位)是由扭曲的Mer-[FeSe_3O_3]八面体网络组成的，这些八面体通过共享的Se2边和O个顶点连接在一起。如磁学、中子粉末衍射和穆斯堡尔谱测量所示，这些磁矩在Tn1=118K以下经历长程磁有序，最初采用具有传播矢量(1/2-δ，0，1/2)(0≤δ≤0.1)的磁结构，其与核结构不相称，并在Pbam1‘(A01/2)000Fe2磁超空间群中描述，直到在92K(TiC)存在一级锁定转变到其中这些Fe2矩形成具有传播矢量(1/2，0，1/2)，可以用空间群36.178 B a B21 m(BNS记法)中的核细胞的2 a×b×2 c膨胀来模拟。在Tn2=52K以下，处于压缩的反[FeSe4O2]八面体环境中的其余三分之一的Fe2+磁矩(Fe1位)发生长程有序化，这从磁学、穆斯堡尔谱和中子衍射图中新的磁布拉格峰的出现可以看出。Fe1站点上的第二组矩的排序导致Fe2站点上的大多数矩的略微重新定向。1.5K时的磁结构用9.40iab空间群中核细胞的2a×2b×2c膨胀来描述(BNS记号)。
Sr2Fe3Se2O3 is a localized-moment iron oxide selenide in which two unusual coordinations for Fe2+ ions form two sublattices in a 2:1 ratio. In the paramagnetic region at room temperature, the compound adopts the crystal structure first reported for Sr2Co3S2O3, crystallizing in space group Pbam with a = 7.8121 Å, b = 10.2375 Å, c = 3.9939 Å, and Z = 2. The sublattice occupied by two-thirds of the iron ions (Fe2 site) is formed by a network of distorted mer-[FeSe3O3] octahedra linked via shared Se2 edges and O vertices forming layers, which connect to other layers by shared Se vertices. As shown by magnetometry, neutron powder diffraction, and Mössbauer spectroscopy measurements, these moments undergo long-range magnetic ordering below TN1 = 118 K, initially adopting a magnetic structure with a propagation vector (1/2 - δ, 0, 1/2) (0 ≤ δ ≤ 0.1) which is incommensurate with the nuclear structure and described in the Pbam1 '( a01/2)000 s magnetic superspace group, until at 92 K ( TINC) there is a first order lock-in transition to a structure in which these Fe2 moments form a magnetic structure with a propagation vector (1/2, 0, 1/2) which may be modeled using a 2 a × b × 2 c expansion of the nuclear cell in space group 36.178 B a b21 m (BNS notation). Below TN2 = 52 K the remaining third of the Fe2+ moments (Fe1 site) which are in a compressed trans-[FeSe4O2] octahedral environment undergo long-range ordering, as is evident from the magnetometry, the Mössbauer spectra, and the appearance of new magnetic Bragg peaks in the neutron diffractograms. The ordering of the second set of moments on the Fe1 sites results in a slight reorientation of the majority moments on the Fe2 sites. The magnetic structure at 1.5 K is described by a 2 a × 2 b × 2 c expansion of the nuclear cell in space group 9.40 I a b (BNS notation).